Various types of manufacturing equipment generate vapors during operation. For example, solder flux applicators that spray soldering flux on circuit boards generate flux vapors. For environmental reasons, it is desirable to exhaust the vapors. Accordingly, most solder flux applicators include a hood overlying the applicator. The hood is connected to an exhaust line having a negative pressure. In this way, flux vapors emanating from the flux applicator are evacuated through the hood and into the exhaust line.
Most soldering flux that is sprayed on circuit boards comprises an alcohol solvent having a small amount of solids dissolved therein. During spraying, the alcohol in the flux evaporates. Because of its low vapor pressure, the evaporated alcohol in the flux vapors exhausted through the hood does not condense on the hood and drip back onto the circuit board. However, there is a trend away from alcohol-based fluxes because of their high Volatile Organic Compounds (VOC) levels. Instead, many circuit board manufacturers now use water-based spray fluxes. Unfortunately, the water in such water-based spray fluxes does not evaporate nearly as quickly as the alcohol in an alcohol-based flux. Consequently, when spraying water-based flux, the vapor exhausted through the hood will contain moisture that condenses on the hood and drips back on the circuit board being sprayed. The condensed moisture that drips back on the circuit board alters its cosmetic appearance, usually requiring that the board be subjected to a cleaning operation which is undesirable.
Thus, there is a need to effectively exhaust water-based flux vapors away from the spray flux applicator while collecting condensing moisture to prevent the condensed moisture from dripping back on the board.